Fuel Trim Chart

I ran into a very informative chart at Eastern Catalytic Tech Tips.

Read more here on their write up here - http://www.easterncatalytic.com/education/tech-tips/fuel-trim-can-be-a-valuable-diagnostic-tool/


I like this diagram they have.

Image credit goes to the Eastern Catalytic.

X-trail: 02 Sensor

I was comparing the O2 sensor signals between the X and a i10. The i10 looks like it has a more healthy 02 signal.

When i floor the pedal, the O2 signal responds shows exactly as described in scannerdanner's tutorial. As for the X, there was plenty noise & deviation from the expected signal form.

Do i have a lazy O2?

Gonna need more tutorials........

X-trail: Fuel Trim

Kind of dragged my feet updating this.

Plugged in the OBD2 donggle. Ran the software.

What did i find?

Short Term Fuel Trim -> +10 range

Long Term Fuel Trim -> +10 range

That would make total fuel trim -> +20% range 

This would mean I have a lean condition

When I throttle the car to >3000RPM total fuel trim drops under 5%. Per scannerdanner's tutorial information, he would say I have a vacuum leak.

So i need to detect where that vacuum leak is by doing one of the below

- spray bottle

- carb cleaner

- propane

- smoke

Which should I choose?